Conventional brake-by-wire systems such as an ECB (Electronically Controlled Brake) system are known in which the target deceleration is calculated based on the stroke value of depression of a brake pedal detected by a brake pedal sensor and the master cylinder pressure detected by a master hydraulic pressure sensor. Thus, if an abnormality (e.g., a gain abnormality) occurs in the master hydraulic pressure sensor, the hydraulic brake system is required to detect such an abnormality in an early stage.
For example, Patent document 1 discloses an apparatus comprising an estimation unit that estimates a first vehicle deceleration based on a brake hydraulic pressure detection value detected by a brake hydraulic pressure detection apparatus, and a detector that detects a second vehicle deceleration which is the actual vehicle deceleration, wherein judgment of whether or not an abnormality has occurred in the brake hydraulic pressure detection value is made based on the difference between the first vehicle deceleration and the second vehicle deceleration.